It depends on where the pressure is places. If the pressure is placed on kids, sure. If it's placed on schools, that's not toxic. The school system in most of the US works under an attitude that the smart kids will do okay, and don't need anything extra. Even gifted and talented programs are fading fast.
The truth is those school system are toxic, abusive torture to someone smart. There were plenty of smart kids I knew -- some smarter than me -- who got horrible grades going through one of these school. Many of them did not, in any real sense, succeed.
Imagine being placed in a room, today, and forced to listen to lectures on what you already know, and be given menial make-work tasks, like adding big numbers and copying letters, and doing that for hours each day. Some people are resilient enough to survive that. Others get pretty broken by it.